Circuit voltage is not stated, but make sure the overload heaters are sized based on the motor-nameplate full-load current and not by lookup in Table 430-150. The table values are intended for branch-circuit and feeder sizing.
The term “motor…service disconnect switch” is mentioned, and seems to be described as possibly applied “downstream” of the individual starters. You may want to instead use fused-disconnect switches applied “upstream” as individual starter and motor disconnecting means—also sufficing as branch-circuit short-circuit and ground-fault protection.
The wiring proposed from a single 60-amp breaker to multiple starters sounds like it may be “daisy-chained,” for which the starter terminals are likely not intended in accommodating larger, possibly multiple conductors. A single disconnecting means for nine motors is not likely permitted in the case of building-ventilation motors.
Note also that local mechanical codes may additionally require individual motor-disconnecting means at each individual motor location—such as with non-fused disconnect switches.